1. Field of the Invention
The present invention relates to a process for preparing a solution of an alkali metal salt of a functionalized alcohol.
2. Discussion of the Background
Alkali metal salts of functionalized alcohols are employed in various fields, for example in the production of copper-containing films in the case of which the sodium salt of 2-amino-1-ethanol or the sodium salt of 2-methylamino-1-ethanol is used, as described in U.S. Pat. No. 5,034,248. Such alkali metal salts of functionalized alcohols can likewise be used for producing pharmaceutical products, for example, the sodium salts of 2-ethylamino-1-ethanol and of 2-amino-1-butanol, which are described in U.S. Pat. No. 4,235,902, or the sodium salt of 2-amino-1-ethanol, which is described in U.S. Pat. No. 4,372,974. A further application of the sodium salt of 2-amino-1-ethanol is described in JP 063 061 024, where it is used for preparing polyphosphazenes.
Alkali metal salts of functionalized alcohols can be prepared, for example, by reacting the free alcohols with alkali metals, as described, for example, in U.S. Pat. No. 4,235,902 or in U.S. Pat. No. 4,372,974. The reaction of functionalized alcohols with alkali metals can likewise be carried out in liquid ammonia as solvent. The disadvantage of these processes is the use of the very reactive metallic sodium for whose use costly safety precautions have to be taken.
A further possible way of preparing such alkali metal salts is the reaction of free alcohols with alkali metal hydrides. Such a reaction for preparing the sodium salt of 2-amino-1-ethanol is described in GB 1 341 375, where this salt is used for preparing heterocycles. A disadvantage of this process is that the expensive sodium hydride has to be used.
A further possibility is to react functionalized alcohols with alkali metal amides or organometallic compounds of alkali metals in order to obtain the alkali metal salts of the functionalized alcohols. Such reactions are described in U.S. Pat. No. 5,629,452, in which diphenylmethylpotassium, diphenylmethylsodium or sodium amide is used. These compounds are complicated to prepare or are expensive. Furthermore, at least in the case of diphenylmethylpotassium and diphenylmethylsodium, the diphenylmethane formed remains in the resulting reaction mixture after the reaction if no further work-up step is carried out.
EP 0 518 013 describes a process for preparing 1-alkoxy-2-dialkylaminoethanes. In the first step, the corresponding amino alcohols are converted by reaction with alkali metal salts of lower alcohols into the respective alkali metal salts of the functionalized alcohols. The reaction is completed by removing the lower alcohol formed from the reaction mixture, with an entrainer being added to the mixture before the work-up by distillation in order to remove the lower alcohol. However, an alternative also proposed by EP 0 518 013 is to employ the respective end products of the ether synthesis as entrainers. However, if the alkali metal salts of the functionalized alcohols are envisaged for purposes other than ether formation, this procedure is ruled out.